Messages in this thread | | | Date | Fri, 2 Oct 2020 11:57:12 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2] drivers/perf: Add support for ARMv8.3-SPE |
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On Wed, Sep 30, 2020 at 05:31:35PM +0800, Wei Li wrote: > Armv8.3 extends the SPE by adding: > - Alignment field in the Events packet, and filtering on this event > using PMSEVFR_EL1. > - Support for the Scalable Vector Extension (SVE). > > The main additions for SVE are: > - Recording the vector length for SVE operations in the Operation Type > packet. It is not possible to filter on vector length. > - Incomplete predicate and empty predicate fields in the Events packet, > and filtering on these events using PMSEVFR_EL1. > > Update the check of pmsevfr for empty/partial predicated SVE and > alignment event in SPE driver. For adaption by the version of SPE, > expose 'pmsver' as cap attribute to userspace. > > Signed-off-by: Wei Li <liwei391@huawei.com> > --- > v1 -> v2: > - Rename 'pmuver' to 'pmsver', change it's type to 'u16' from 'int'. > (Suggested by Will and Leo.) > - Expose 'pmsver' as cap attribute through sysfs, instead of printing. > (Suggested by Will.) > --- > arch/arm64/include/asm/sysreg.h | 4 +++- > drivers/perf/arm_spe_pmu.c | 18 ++++++++++++++++-- > 2 files changed, 19 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h > index 554a7e8ecb07..f4f9c1fc6398 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -281,7 +281,6 @@ > #define SYS_PMSFCR_EL1_ST_SHIFT 18 > > #define SYS_PMSEVFR_EL1 sys_reg(3, 0, 9, 9, 5) > -#define SYS_PMSEVFR_EL1_RES0 0x0000ffff00ff0f55UL > > #define SYS_PMSLATFR_EL1 sys_reg(3, 0, 9, 9, 6) > #define SYS_PMSLATFR_EL1_MINLAT_SHIFT 0 > @@ -787,6 +786,9 @@ > #define ID_AA64DFR0_PMUVER_8_5 0x6 > #define ID_AA64DFR0_PMUVER_IMP_DEF 0xf > > +#define ID_AA64DFR0_PMSVER_8_2 0x1 > +#define ID_AA64DFR0_PMSVER_8_3 0x2 > + > #define ID_DFR0_PERFMON_SHIFT 24 > > #define ID_DFR0_PERFMON_8_1 0x4 > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index cc00915ad6d1..52e7869f5621 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -54,7 +54,7 @@ struct arm_spe_pmu { > struct hlist_node hotplug_node; > > int irq; /* PPI */ > - > + u16 pmsver; > u16 min_period; > u16 counter_sz; > > @@ -80,6 +80,15 @@ struct arm_spe_pmu { > /* Keep track of our dynamic hotplug state */ > static enum cpuhp_state arm_spe_pmu_online; > > +static u64 sys_pmsevfr_el1_mask[] = { > + [ID_AA64DFR0_PMSVER_8_2] = GENMASK_ULL(63, 48) | GENMASK_ULL(31, 24) | > + GENMASK_ULL(15, 12) | BIT_ULL(7) | BIT_ULL(5) | BIT_ULL(3) | > + BIT_ULL(1), > + [ID_AA64DFR0_PMSVER_8_3] = GENMASK_ULL(63, 48) | GENMASK_ULL(31, 24) | > + GENMASK_ULL(18, 17) | GENMASK_ULL(15, 11) | BIT_ULL(7) | > + BIT_ULL(5) | BIT_ULL(3) | BIT_ULL(1), > +};
Ok, so I finally figured out what I don't like about this: it's the fact that the RES0 mask only ever reduces, but we have no way of ensuring that by construction with this approach. In other words, it's a bit brittle to keep all of these things defined entirely separately from one another.
How about a small change so that we define things like:
#define SYS_PMSEVFR_EL1_RES0_8_2 SYS_PMSEVFR_EL1_RES0 & ~(...)
#define SYS_PMSEVFR_EL1_RES0_8_3 SYS_PMSEVFR_EL1_RES0_8_2 & ~(...)
where the '...' parts identify the bits that are no longer RES0 for that version of the architecture?
What do you think?
Will
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